Problem : Plane wall compuonded from 2 or more faces.Radiosity doesn`t recognize that faces lies in the same plane.So there is evident border between faces,(even if they have same material of course).Playing with radiosity buttons can improve final solution a bit,but anyway, it seem to me like illogical.
Solution ?: Radiosity could take faces(with same material,vertex orientation,etc.) in the same plane like one face. [/b]

also, I often force seams by selecting the flat/rounded regions and splitting them from the surrundings in edit mode (y key, then confirm or exit grab mode) so that the entire mesh can be set smoothed, which will reduce the vertex count after the radiosity calculation (though not the face count), and allows better control over where the seams are

Clovek wrote:Thanks.I`ll play with it.BUT it would be much better if radiosity will working "independently" from exactmesh model, and make its own seamless model for counting.There is so much redundant work.

Of course radiosity doesn`t work that way now.But it could be.Example: Bigger face could be split(just for radiosity patch) according to the smaller adjacent face in the same plane,and without any seams.Where is the problem?

Clovek wrote:Of course radiosity doesn`t work that way now.But it could be.Example: Bigger face could be split(just for radiosity patch) according to the smaller adjacent face in the same plane,and without any seams.Where is the problem?

clovek - you may be right: however it would probably take a complete reprogram of the radiosity algorithmn to fix I think, given the way the solution is stored "per vertex" at the moment....

On the other hand, these issues are pretty easy to avoid most of the time: first of all, make sure you have removed all double vertices! You had 114 in the mesh in the middle of your scene, and removing these gave a pretty good improvement already.

Secondly, if you have doors etc, try modelling these into the mesh instead of making them from separate blocks (this is difficult to explain but easy to do!). But anyway, it took me ~1 minute to fix the section in the middle of your scene with the knife tool - here's my version!:

Pity that knife tool havn`t precision CAD option.(....or I didn`t found it...)
(something like: I want to split this face from this point(x,y,z) to that point(x,y,z)).Grid is not useful for everything.(or not so fast actually)
I`ll hope that "CAD-python team" improve that, or add something helpful.